The problems of fugitive dust are well known and encountered in the constructions industries, the coal industry, and other mining industries. Fugitive dust even exists in agriculture and food processing industries. Dust and other solid particles can also be suspended in air and pose environmental issues in populated or environmentally sensitive areas. Such particles also pose detrimental health effects.
One example, hydraulic fracturing, known as “fracking” or “hydrofracking” in the oil and gas industry, is the propagation of fractures in a rock layer to enhance the release of oil and natural gas into the well bore for extraction and subsequent refining. In hydraulic fracturing, a proppant is used at a large amount to keep the fractures in the rock open. Hundreds of tons of proppant are used for fracturing a well. The proppant often contains silica such as silica sand, or resin coated silica sand. When the proppant is processed, large amounts of dust containing silica and other components are evolved. The silica dust is created during the movement of the proppant by shearing of the sand particles as they slide along one another. In addition to potential contamination of the air and water nearby, the silica dust also exposes workers at the well site, at the mines and at the processing facilities to possible inhalation. Such an exposure can lead to a lung disease called silicosis.
Silicosis is a form of an occupational lung disease caused by inhalation of crystalized silica dust. It is characterized by inflammation and scarring in forms of nodular lesions in the upper lobes of the lungs. When small silica dust particles are inhaled (<10 μm) they can imbed themselves in the air exchange portion of workers' lungs (alveoli). The lungs cannot clear themselves of the imbedded dust by mucous or coughing, thus chronic exposure to respirable silica can cause a buildup of these particles and lead to silicosis.
Conventional dust suppression systems include both mechanical and chemical methods. Dust collection equipment includes devices which capture entrained dust, induce the dust to settle, or contain the dust. The most common method, however, is the wetting of dust particles (such as coal) with water. Water is inexpensive and large quantities can be applied. However, its effectiveness as a dust suppressant is less than satisfactory. The addition of water may cause additional problems such as a decrease in the specific heating value of coal. Other aqueous additives such as surfactants or foaming agents, and aqueous compositions comprising asphalt emulsions or other organic coating materials are also used to suppress dust. In addition to aqueous solutions, oils and resins are also used to reduce or eliminate coal dust. Oil spraying includes the use of crude, residual, waste or fuel oils. Synthetic and natural polymers can be coated onto coal to reduce dust. However, the prior additives and compositions have limited applicability and effectiveness.